removed sender_format from config
store both, sender name and address in mail objects
mailcollector: removed error messages from subject and sender strings
user script plugin: fixed script arg
mailchecker, plugins: pass both, new and all mails to MAILS_ADDED hook
mailchecker: fixed wrong count for filtered new mails
libnotify plugin: added some constants, enabled single notification mode, uncommented notification_id
spamfilter plugin: renamed variable
